Allyl acetone having the structure: ##STR2## is a valuable substance useful as an intermediate in the formation of compounds valuable for use in perfumery such as, for example, the compound 1-(2,6,6-trimethyl-cyclohexen-1-yl)-1,6-heptadien-3-one which is produced from allyl acetone according to the reaction scheme: ##STR3## wherein the dashed lines signify a mixture of double bond isomers.
The instant invention describes a process for preparing allyl acetone by means of allylating an acetoacetic ester in the presence of (i) a phase transfer agent and (ii) in a two phase system.
In U.S. Pat. No. 4,010,207 a process is described for the preparation of substituted unsaturated aldehydes according to the reaction: ##STR4## wherein one of the dashed lines is a double bond and the other of the dashed lines is a single bond; wherein R.sub.1 is allyl or benzyl, R.sub.2 is one of alkyl, aryl, alkenyl or alkoxyalkyl and R.sub.3 and R.sub.4 are each hydrogen or alkyl, with the proviso that when R.sub.3 is alkyl the dashed line between the .beta. carbon atom and the .gamma. carbon atom represents a double bond and when R.sub.3 is hydrogen, either of the dashed lines is a double bond, wherein X is chloro or bromo, and wherein M is alkali metal, the reaction being carried out (1) using a phase transfer agent, and (2) in a two phase system.
The instant reaction is different in kind from the reaction described and claimed in U.S. Pat. No. 4,010,207.
German Pat. No. 1,244,784, issued on July 20, 1967, discloses the reaction: ##STR5## wherein R can be one of alkyl, alkenyl, allyl, propargyl, cyclohexyl or benzyl; X is chloro or bromo and R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 can be hydrogen, alkyl, alkenyl or phenyl. The reaction of the German Patent is limited to ketones. Although such ketones could be unsaturated, the nature of the reaction is different in kind from the reaction of the instant invention.
Chemical Abstracts, vol. 81 (1974) 135501 g, summarizes a paper by Tsukasa, et al. entitled: "Alkylation of alpha, beta-unsaturated cyclic ketones. Synthesis of jasmones". In this case cis and trans jasmones are synthesized by rection of 3-methyl-2-cyclopentenone with an alkyl halide in the presence of powdered potassium hydroxide and dimethyl sulfoxide; the Chemical Abstracts synthesis being carried out with dimethyl sulfoxide on a ketone rather than an aldehyde. This process is different in kind from the process of the instant invention.
In U.S. Pat. No. 4,045,489, issued on Aug. 30, 1977, a process is described for the preparation of cis-jasmone according to the reaction: ##STR6## wherein X is chloro or bromo and wherein M is alkali metal, the reaction being carried out (1) using a "phase transfer agent" and (2) in a two phase system.
The reaction of the instant invention for the preparation of allyl acetone is different in kind from the reaction of U.S. Pat. No. 4,045,489, issued on Aug. 30, 1977.
U.S. Pat. No. 4,124,644, issued on Nov. 7, 1978, describes a process for the preparation of substituted oxyacetaldehydes and acetals thereof according to the reaction sequence: ##STR7## wherein R.sub.1 and R.sub.2 are each lower alkyl or R.sub.1 and R.sub.2, taken together form a lower alkylene group; wherein R.sub.3 is alkyl, alkenyl or alkadienyl and X is halogen selected from the group consisting of chlorine and bromine, the reaction (i) being carried out (1) using a "phase transfer agent" and (2) in a two phase system.
The process of U.S. Pat. No. 4,124,644 is different in kind from the process for making allyl acetone of the instant invention.
In J. Org. Chem., Vol. 39, No. 22, 1974 at page 3271, an article by Durst & Liebeskind entitled, "Phase Transfer Catalysis. The Acetoacetic Ester Condensation" indicates that reaction of allyl chloride with methyl acetoacetate gives rise to a 30% yield of 4-carbomethoxy-1-hexen-5-one and reaction of methyl acetoacetate with allyl bromide in the presence of an Aliquat 336.RTM. catalyst gives rise to a 94.7% yield of 4-carbomethoxy-1-hexen-5-one. The reaction is carried out however in the presence of anhydrous benzene which gives rise to the danger of causing minute traces of benzene to exist in the final desired product which is to be used for its organoleptic properties in perfumery. The potential presence of such solvent is unacceptable in the perfumery field.
At page 4682 of J. Org. Chem., Vol. 43, No. 24, 1978 sodium and potassium carbonates are indicated to be useful as efficient strong bases in solid-liquid two phase systems in, for example, the alkylation of 9-substituted fluorene derivatives, thusly: ##STR8## The Chemical Communications reference, however, does not suggest the use of sodium or potassium carbonates in a reaction such as the instant one. It is noteworthy that nowhere in the list of thirteen "starting" compounds is an allyl halide mentioned.